1. Field of the Invention
This invention relates to digital transmission arrangements and is more particularly concerned with digital transmission arrangements for transmitting digital signals between devices which operate with different data transmission procedures and with different data formats.
2. Description of the Prior Art
It is already known, in conjunction with a transmission of digital signals having differing data transmission procedures and differing data formats between transmitting and receiving installations, to adjust the individual receiving installations in accordance with respective data transmission procedure and the respective data format. In these receiving installations, it is a matter of teleprinter machines which are to be designed both for receiving teleprinter signals (telex operation) as well as for receiving office printergrams (teletex operation). The appertaining machines, moreover, are designed in accordance with the transmission of signals with two different transmission procedures and data formats. Whereas one works in telex operation with the data transmission rate of 50 bit/sec. and with a start-stop control, teletex operation is a matter of a synchronous data transmission operation with a data transmission rate of, for example, 2400 bit/sec. The transfer apparatus, therefore, required in the individual office machines, however, require a significant circuit expense.
The German patent application P 29 12 649.6 reveals a way to make do with lower circuit expense in comparison thereto in order to be able to transmit digital signals with mutually different data transmission procedures and in mutually different data formats between transmitting devices and receiving devices.
This German application relates to a circuit arrangement for the transmission of digital signals between transmitting and/or receiving installations operating in accordance with a first data transmission procedure and with a first data format and transmission and/or receiving installations operating in accordance with a second data transmission procedure different from the first data transmission procedure, as well as with a second data format differing from the first data format, via a switching system. What is meant by the term "data transmission procedure" is both the data transmission rate and the type of transmission of signals.
What is viewed as being essential in the circuit arrangement indicated above is that the transmission and/or receiving installation designed for operation with the first data transmission procedure and the first data format and the transmission and/or receiving installations designed for operation with the second data transmission procedure and the second data format are connected to separate termination circuits provided for the respective data transmission procedure and the respective data format in a first group or, respectively, in a second group of termination circuits of the switching system and that a conversion unit is connected to at least one termination circuit of each group of termination circuits into which conversion unit all signals emitted by a transmission installation belonging to one message in accordance with the first data transmission procedure and with the first data format or, respectively, in accordance with the second data transmission procedure and with a second data format can be respectively enscribed, and from which conversion unit, subsequently, all signals belonging to the respective message can be output and emitted in accordance with a second or, respectively, with the first data transmission procedure and with the second or, respectively, first data format to the receiving installation which is receiving signals.
A relatively high memory expense occurs, however, in the converter unit due to these features.